Cold cathode fluorescent lamp



C. HERZOG COLD CATHODE FLUORESCENT LAMP Dec. 23, 1,947.

2 Sheets-Sheet 1 Filed June 12, 1945 y l Inuon Carl, Harzoff,

4 i w m w Dec. 23, 1947. c. HERZOG 2,433,218

COLD CATHODE -FLUORESCENT LAMP Filed June 12, 1945 2 Sheets-Sheet 2 "Ulm: 3445 Cwr, Harm?,

' Patented Dec.v 23, 1947 UNITED STATES PATENT OFFICE 2,433,218 com cA'rnonE FLUonEscEN'r LAMP Carl Herzog, Belleville, N. J. Application June 12, 1945, Serial No. 599,011

4 Claims. (Cl. 176-122) My invention relates to cold cathode fluorescent lamps.

An important object of the invention is to provide a lamp of the above mentioned character having the cold electrode units arranged within and fused to the glass tube and the tubular electrodes spaced from the glass tube.

A further object of the invention isto provide a lamp of the above mentioned character having contact elements formed upon or carried by the electrode units, thus dispensing with the use of the ordinary insulating discs secured to the glass tube and carrying the separate contact elements.

A further object of the invention is to reduce the heat transfer between the tubular electrode and the spacing ring of the electrode unit.

Other objects and advantages of the invention will be apparent during the course of the following description.

This application is a continuation in part of my copending applications for Method for pro-4 ducing electronic devices, led January-25, 1944, Serial No. 519,666, `which issued December 25, 1945, as United States Patent 2,391,572, and Method of and apparatus for making cold cathode iluorescent lamps or the like, led March 7, 1944, Serial No. 525,446, which issued December 25, 1945, as United States Patent 2,391,573.

In the accompanying drawings forming a part of this application and in which like numerals are employed to designate like parts throughout the same,

Figure 1 is an enlarged central longitudinal section through a complete cold cathode lamp embodying my invention,

Figure 2 is a transverse section taken on line 2-2 of Figure 1,

Figure 3 is yan enlarged central longitudinal section through a complete cold cathode lamp embodying a second form of the invention,

' Figure 4 is a transverse section taken on line 4-4 of Figure 3,

Figure 5 is an enlarged central longitudinal 'section through a third form of cold cathode lamp embodying my invention,

Figure 6 is a transverse section taken on line 6-6 oi Figure 5, v

Figure 7 is a transverse section taken on line 1--1 of Figure 5,

Figure 8 is a central longitudinal section through a fourth form of cold cathode fluorescent lamp embodying my inven-tion,

Figure 9 is a transverse section taken on line 9-9of Figure 8,

Figure 10 is an enlarged central longitudinal section through a fifth form of cold cathode fiuorescent lamp embodying my invention, and

Figure 11 is a transverse section taken on line Il--Ii of Figure 10.

In all forms of the invention, Figures 1-11 inclusive, the numeral 20 designates a glass tube, constituting the envelope of a cold cathode iluorescent lamp. 'Ihis tube may be of any suitable diameter and length. These tubes are fre- A quently a half-inch in diameter and eight feet long, although the dimensions may be widely varied. 'I'he inner surface of the glass tube 20 is covered or coated with a coating composition Y 2| containing a nely divided luminescent or iluorescent material, and the coating is dried. I may employ the coating composition disclosed in the patent to T. M. Cortese, 2,318,060, and this coating may be applied and dried in accordance with the method disclosed in the Cortese patent. This coating may be baked in a separate oven, or the baking may occur as a step in assembling the parts of the lamp, as disclosed in my said applications 519,666 and 525,446. The fluorescent coating 2i is baked and firmly anchored to the inner face of the tube 20. The coating is iirst applied to the inner face of the tube 20 and dried, but not baked, and may then extend throughout the entire length of the tube 20, and this dried coating is removed from the ends of the tube 20 to points 22, leaving clean or uncoated end zones 23.

In Figures 1 and 2, integral electrode units 24 are provided, which are tubular and are arranged in the opposite uncoated zones 23. Each integral unit 24 is made of a special commercial chromeiron alloy having the same expansion coeflicient as the glass tube 20. Each unit 24' comprises a tubular electrode 24 and an enlarged annular spacing retaining ring 26, connected with the tubular electrode 24 by a. tapered portion 21. The tubular electrode unit 24' includes 'an outer head 28, and this head carries a reduced cup-shaped contact 29, extending axially outwardly, and having a closed head 30. The tubular electrode 24, spacing retaining ring 26 and contact 29 are preferably cylindrical and are arranged in concentric relation. 4 The spacing retaining ring 26 has a considerably larger diameter than the tubular electrode 24. 'Ihe inner end of the tubular electrode 24 is open, as shown. The interior of the electrode unit 24' is coated with an electron emitting material 30', extending over the entire surface thereof, as shown.

The retaining ring 26 is arranged within each uncoated zone 23, and the glass tube 26 is heated, contracted and fused to the periphery of the spacing retaining ring 26, forming a vacuum tight Joint. The -spaclng retaining ring 26 holds the tubular electrode in spaced concentric relation with the inner face of the tube 20, as shown. The retaining ring 26 may have the end of the glass tube 20 fused thereto by the methods shown in my copending applications 519,666 or 525,446, or by other methods. The tube 20 in the completed lamp has a suitable degree of vacuum.

In Figures 3 and 4, the numeral 3|' designates tubular electrode units, including tubular electrodes 3|, which have outer heads or closed ends 32', and inner open ends, as shown. These tubular electrodes are `formed of the purest iron obtainable and have their interiors coated with an electron emitting material 32, extending over the entire surface thereof, as shown. Each tubular electrode 3| is press fitted into a cup-shaped contact 33, carried by a head 34, formed upon a spacing retaining ring 35, having a larger diameter than the tubular electrode 3|. The contact 33 has an outer head 36, as shown. The ring 35, head 34, and contact 33 are integral and are made of a special commercial chrome-iron alloy having the same coeflicient of expansion as the glass, while the tubular electrode 3| is made of pure iron. 'I'he elements 3|, 35 and 33 are cylindrical and are arranged in concentric relation.

The spacing retaining ring 35 is arranged within each end zone 23 of the tube 20 and the end zone is heated, contracted and fused to the periphery of the ring 35, forming a vacuum tight joint, as explained in connection with the first form of the invention. The spacing retaining ring 35 holds the tubular electrode 3| in spaced concentric relation to the interior of the tube 20.

In Figures 5 and 6, I have shown a tubular electrode unit 31', including the same retaining ring 35 and contact 33. This unit 31 also includes a tubular electrode 31, which is identical with the electrode 3 and has an outer closed end or head 38. The interior of the tubular electrode 31 is coated with an electron emitting material 38', extending over the entire surface thereof.

The tubular electrodes 31 are not inserted into the cup-shaped contacts 33, but have the centers of their heads 38 Welded to wires 33, the outer ends of which are Welded to the centers of the heads 36. The wires 39 support the tubular electrodes 31 in spaced concentric relation to the contacts 33 and the glass tube 20. The heads 38 are preferably arranged slightly inwardly of the spacing retaining rings 35.

It is thus seen that I have provided a cylindrical metallic shell including a long side 35 and a at head 34 disposed at a right angle to the longitudinal axis of the side 35. The cup shaped contact 33 is arranged concentric with the head 34 and projects outwardly of the head 34. The cup shaped contact 33 has a head 36. The side 35 of the shell is arranged within the glass tube 2| and the end of the glass tube terminates adjacent to the head 34.

The spacing retaining rings 35 are arranged within the zones 23 of the glass tube and the ends of the glass tube are heated, contracted and fused to the peripheries of the rings 35, as explained in connection with the rst form of the invention. A suitable vacuum is formed in the tube 20.

In Figures 8 and 9, the tubular electrodes 31 1 4 oppositely arranged. The wires 40 have radial extensions 4|, welded to the head 34. All other parts ot the lamp remain identical with those shown and described in connection with the form of the invention shown in Figure 5.

In Figures 10 and 1l, the tubular electrodes 31 have their heads 38 welded to a generally U- shaped metal ribbon or strip 42, having radial extensions 43, welded to the heads 34. All other parts of the lamp remain identical with that shown and described in Figure 5.

The advantage oi' the constructions shown in Figures 5-11 inclusive, is that the tubularv electrodes are spaced from thecontacts 33. and spacing retaining rings 35, and are connected therewith by the long relatively small Wire or wires or ribbon. and the amount of heat which is transmitted by conduction from the tubular electrodes to the caps 33 and rings 35 is therefore materially reduced. Thiais advantageous after the lamp has been made and is operating in use.

The contacts 29 and 33 extend axially outwardly beyond the glass tubes 20 of the lamps and these contacts are connected with the terminals of the source of current. When the current is turned on, the lamps will operate in the usual manner. The construction eliminates the use of insulating caps ordinarily secured to the ends of the glass tube and carrying separate contacts.

It is to be understood that the forms of my invention herewith shown and described are to be taken as preferred examples of the same and that various changes in the shape, size, and arrangement of parts may be resorted to without departing from the spirit of my invention or the scope of the subjoined claims.

Having thus described my invention, what I claim is:

1. A cold cathode fluorescent lamp, comprising a glass tube open at its ends and having its inner surface coated with fluorescent material, a substantially cylindrical metal shell for each end of the glass tube and having substantially the same coeillcient of expansion as the glass tube, the metal shell including a long substantially cylindrical side and an outer substantially fiat head disposed at substantially a right angle to the longitudinal axis of the side and a cup shaped contact of smaller diameter than the shell side and arranged upon the outer face of the shell head and carried by the shell head and extending axially outwardly beyond the shell head, the cup shaped contact being substantially concentric with the shell side and including an outer head. the shell side being positioned within the end portion of the glass tube and the glass tube being welded to the outer face of the shell side and terminating substantially at the head of the shell side, a tubular metal electrode having its inner end open and having a head at its outer end and provided with electron emitting material, the tubular electrode being arranged within the glass tube and extending axially thereof and projecting inwardly throughout the major portion of its length beyond the shell side, and a relatively long wire having a relatively small diameter and attached to the outer head of the tubular electrode and the outer head of the cup shaped contact element and supporting the tubular electrode substantially concentric with relation to the glass tube, the arrangement being such that there is a low heat transfer between the tubular electrode and shell without the use of insulating material. 2. A cold cathode fluorescent lamp, comprising a glass tube open at its ends and having its inner face coated with fluorescent material, a

sheet metal shell for each end of the' glas: tube` and having substantially the same coefcient of expansion as the glass tube, the sheet metal shell including a long substantially cylindrical side and an outer substantially flat head disposed at substantially a right angle to the longitudinal axis of the side and a cup shaped contact of smaller diameter than the shell side and arranged upon the outer face of the shell'head and carried by the shell head and extending axially outwardly beyond the shell head, the cup shaped contact being substantially concentric with the shell side, the shell side being positioned within the end portion of the glass tube and the glass tube being welded to the outer face of the shell side and terminating substantially at the head of the shell, a tubular metal electrode having its inner end open and having a head at its outer end and provided with electron emitting material, the tubular electrode being arranged within the glass tube and'extending axially thereof and having its outer head disposed adjacent to the inner end of the shell side, and a long wire having a relatively small diameter and attached to the tubular electrode adjacent to its outer head and secured to the sheet metal shell and supporting the tubular electrode substantially concentric with relation-to the glass tube, the arrangement being such that there is a low heat transfer between the tubular electrode and shell without the use of insulating material.

3. A cold cathode fluorescent lamp, comprislong wires having relatively small diameters secured to the side of the tubular electrode and the shell head and supporting the tubular electrode substantially concentric with relation to the glass tube, the arrangement being such that there is a low heat transfer between the tubular electrode and shell without the use of insulating material.

4. A cold cathode fluorescent lamp, comprising a glass tube open at its ends and having its inner lace coated with fluorescent material, a sheet metal shell for each end of the glass tube and having substantially the same coefficient of expansion-as the glass tube, the sheet meta shell including a long substantially cylindrical side and an outer substantially flat head disposed at substantially a right angle to the longitudinal axis of the side and a cup shaped contact of smaller diameter than the shell side and arranged upon the outer face of the shell head and carried by the shell head and extending axially outwardly beyond the shell head, the cup shaped contact being substantially concentric with the shell side, the shell side being positioned within the end portion of the glass tube and the glass tube being welded to the outer face of the shell side and terminating substantially at the head of the shell, a tubular metal electrode having its inner end open and having a head at its outer end and provided with electron emitting material, the tubular electrode being arranged within the glass tube-and extending axially thereof and having its outer head disposed adjacent to the inner end of ing a glass tube open at its endsand having its inner face coated with fluorescent material, a sheet metal shell for each end of the glass tube and having substantially the same coeliicient of expansion as the glass tube, the sheet metal shell including a long substantially cylindrical side and an outer substantially flat head disposed at substantially a right angle to the longitudinal axis oi the side and a cup shaped contact of smaller diameter than the shell side and arranged upon the outer face of the shell head and carried by the shell head and extending axially outwardly beyond the shell head, the cup shaped contact being substantially concentric with the shell side, the shell side being positioned Within the end portion of the glass tube and the glass tube being welded to the outer face of the shell side and terminating substantially at the head of the shell, a tubular metal electrode having its inner end open and having a head at its outer end and provided with electron emitting mate rial, the tubular electrode being arranged within the glass tube and extending axially thereof and having its outer head disposed adjacent to the inner end of the shell side, and relatively the shell side, and a generally U-shaped wire f bracket attached to the electrode outer head and the shell head and serving to support the tubular electrode substantially concentric within the glass tube, the bracket including relatively long wire sections having relatively small diameters.

CARL HERZOG.

REFERENCES CITED The following references are of record in the fllevof this patent: 

